Tanning material containing alkali-earth metals and heavy metals and process of making same



Patented Feb. 17,1925.

UNITED STATES. PATENT OFFICE.

' osoan IbW-BEERJOF rmxron'r-on-wnn-mun, GERMANY, assienon so canmscnnrnnrxnnwonms A. a, OF FRANKFORT-ON-THEMAJIN; GERMANY, a

l CORPORATION OF GERMANY.

'rnmino coiwmmme AfLKALI-EARTH METALs Ann ,rnocxss or MAKING same No Drawing".

To all whom army concern. Be it known that I, OSCAR a citizen of the Czechoslovakian Republic, residing at Frank fort on-the-Main, Germany, 5 have invented certain new and useful Improvement in Tanning Materials containing Alkali-Earth Metals and Heavy Metals and Processes of Making Same, of which the following is a'specification. 1

My present invention relates to a process of preparing tanning substances and of tanning animal hides.

Hitherto artificial tanning substances ob tained by coupling organic compounds ll either directly with each other or by atoms or by atomic groups (see German Patents Nos. 265,855, 2665139, and 280,233) .have been used for tanning animal'hides. According to the specifications of these patents 0 such tanning substances or mixtures thereof with other tanningor non-tanning materials,-which however merely constitute mechanical miXtures,can -only be used in acid solution. The said specifications do not contain any statements as to employing the respective substances in neutral solution, from which it must be concluded that they are intended to be used only ,inthe usual acid solution. Moreoverfneither the artificial tanning substances above referred'to nor the alkali metal salts derived therefrom possess in neutral solution,(tested on Congo paper) the cha'racter of a tanning agent and do not precipitate animal glue;

tion thatsalts' can be formed from tanning substancesproduced by the chemicalreactionvof artificial tanningmaterials consisting of organic componentsficoupled with aluminium or chromium compounds and having the general formula 5 link, such as an atom oratomie group an Me for an' allgalineearth metal or a heavy metal, which precipitate gluecopiously in a solution neutral'to Congo paper suitable for Low-BEER, 1

pensed with;

Now I have made the surprising observe-i Application filed March so, 1921. Serial Ho. 457,159.- 7

tanning animal hidesfl The use such solutions for tanning hides has the great advantage th'at the injurious actionof theacids which, if not washed outof the fin ished leather, gives a leather which becomes 1 cracked is avoided and ,that the onerous washing out of the finished leathei which lmpairs the yield of the leather can be dis- The tanning action of above men- I tinned salts of {tanning} substances which 1 yield solutions neutralto Congo pa erhas hitherto been unknowniand in VIEW 0 the behav our of the corresponding alkali metal salts this action could not be foreseen, others wise the above-mentioned German "specifications would certainly have particularly pointed out their formation and application 1n View of the great advantagesto be derived therefrom, a a

The process for preparing said tanning ,salts which yield solutions neutral to Congo paper may be advantageously car: ried out as set forth in the following examples:' j, li'a'a-mple 1.-150 kilos'of coalitar oil are s'ulfonated with 150 kilos ofl sulfuric acid of 98 per cent strengthand theproductis carefully condensed with -k1los of .a formaldehyde solution 01540 per cent strength first at 'a temperature of 4060 O. and finally at 75 C. After the mass has become stiif it is dissolved by introducing steam. The excess of sulfuric acid isthen neutralized by means of potash solution untilthe liquid is only faintly acid whereupon aluminium hydroxid .iis added-until a test doesnot chan e the color oicongopaper. The solution t'us obtained may be used directly for tanning, itshows on litmus paper A an acid-reaction, on Congo paper a neutral 1 reaction and precipitates gluefreely with a grey-color." The dry substance obtained by evaporation chars when heated, without previously melting and is insoluble in ether andbenzene. I I a Emmi/2910 2.-.-100 kilos of coal tarphenols of meltlng point ,185200 C.are mixed with 27 5 kilos of crystallized sodium sulfite, 275 litres ofwater and 150 lbs. of a formaldehyde solution of 30' per cent stren th and this mixture -is heated in an autoc ave for about 8 hours at140-150 C.

The condensation mass is acidified by means of sulfuric acid and the sulfurous acid is boiled out. The product is then neutralized with chromium oxide hydrate until it does no longer change the color of Congo paper. The so ution shows on litmus paper an acid reaction, but on Congo paper a neutral reaction; it precipitates glue with a brownish color. The dry substance chars when heated, without first melting; it is soluble in water but insoluble in. ether and benzene.

Example 52-75 kilos of naphthalene and 75 kilos of phenol are sulfonated for 8 hours at 120 C. with 150 kilos of sulfuric acid of 98 per cent strength and the product is condensed at 6080 C. with 75 kilos of a formaldehyde solution of 30 per cent strength until a test with a glue solution shows no further increase of the precipitate. The mass thus obtained before getting stiff is diluted with 100 litres of water, neutralized with calcium hydroxide until it shows only a slightly acid reaction and is then filtered. Into the solution jbasic chromium sulfate is introduced until it does not change the color of Congo paper; it shows on litmus paper an acid reaction, on Congo paper a neutral reaction and precipitates. glue with a brown color. The dry substance chars when heated,- witho'ut melting; it is soluble in water, insoluble in ether and benzene.

Example 4.100 kilos of creosote oil are I sulfonated with 150 kilos of sulfuric acid.

kilos of a formaldehyde solution of 30 per" cent strength. The reaction mass is of 98 .per cent strength and the product is condensed as indicated in example 3 with diluted with water and mixed with a solution of 150 kilos of chromium sulfate and 200 kilos of caustic soda solution of 40 B. The tanning liquor thus obtained gives an acid reaction on litmus paper, but a neutral reaction on Congo paper-and it precipitates glue with a greyish-green color. The dry substance chars when heated, without previously melting and is insoluble in ether and bensene.

E sample 5. 75 kilos of naphthalene and 75 kilos of phenol are sulfonated as indicated in example 3 with 150 kilos of sulfuric acid of 98 per cent strength and then condensed with 75 kilos of a formaldehyde solution of 30 per cent strength. The reaction mixture obtained before getting stiff is diluted with 100 litres of water and after adding thereto 50 kilos of tanning it is coupled at 80 C. with 50 kilos of a formaldehyde solution of 30 per cent strength. There are then introduced 85 lbs; of potash solution of 36 B. and the whole is neutralized with aluminium hydroxide until a test on Congo paper does not change. its color. The solution shows a neutral' reactionand precipitates glue with a grey color; the dry substance has the same properties as that obtainable according to example 4:.

E wample 6.-23 kilos of 2.6 naphthoisulfonic acid are mixed with a solution of 18 kilos of glucose in 10 litres of water and this mixture is subjected to reaction at Waterbath temperature with 10 kilos of a formaldehyde solution of 30 per cent strength. The product is dissolved in hot water, filtered and chromium hydroxide is added thereto until a test on Congo paper does not change the color of the latter. The solution shows 011 litmus paper an acid reaction, on Congo paper a neutral reaction, and precipitates glue with .1 greyish green color. The dry substance does not show any melting point, but gets charred when heated and is soluble in the aforementioned organic solvents.

The hereinbefore described neutral tanning substances are soluble in water and possess the properties of the usual tanning agents; they can be employed alone or mixed with other tanning agents or other ingredients and they are alone suitable for the combined tannings process. If the aqueous solutions of the hereinbefore or hereinafter described. tanning substances are strongly diluted there is a separation of flakes which can however be prevented by adding suitable bodies such as for instance, waste liquor from sulfite cellulose or its metallic compounds.

The process for tanning leather by means of the before-mentioned salts of tanning substances which give on Congo paper a neutral reaction, can be carried out in the following manner:

The prepared unhaired skin is treated with a tanning liquor of 23% strength of the tanning substances composed as indicated in examples 1-6. The tanning is effected according .to thekind of skin, in tan pits, in the reel or in the fulling trough, the strength of the liquor being adjusted and the duration of tanning modified accordingly.

It has been proved that when employing the above described process the unhaired skins can without being previously heated be tanneddirectly in the vat in a short time without fear of producing a leather having a'rough grain.

In the placeof the above-described artificial tanningagents produced from coupled organic compounds .and aluminium or chromium compounds, there may be obtained other new tanning: substances .by treating the same with compoundsof other heavy metals, which new tanningsubstances have also the advantage of stron'gl precipitating glue in a solution neutral to G dngo paper, of tanning animal hides and of being soluble in' water;

Such heavy metal compounds are for in- V Y ot a; formaldehyde solution of 30 percent stance cerium hydroxide, stannous cerium sulfate and the like.

Further experiments made along the lines chloride,

of my above mentioned observations have proved that such, artificial tanning subrelatively larger quantities of heav metals are deposited 1n the animal hides. he new products consequently constitute complex compounds of basic. metal salts possessing the further advantageous property of tanning animal hides in a solution neutral to Con 0 paper. i

T16 tanning with these new tanning substances is also carried out, according to the kind of unhaired skin, in tan pits, in the reel or the fulling trough, the strength of the liquor being adjusted and the duration of tanningmodified accordingly. .These compounds of tanning substances possess the properties of the ordinary tanning agents and can be employed alone or mixedwith other suitable ingredientsand they are also adapted forthe combined tanningprocess.

,Ewmnple Vi -100 kilos of v C. are mixed with 275 kilos of crystallized sodium sulfite.

- 275 kilos of water and 150 kilos of a for 3 maldehyde solution of (per cent strength and this mixture is heate in an autoclave for 8 hours at PLO-150 G. The condensation mass is acidified by means of sulfuric acid andthe sulfurous acid is boiled .out. The product is then neutralized by means- Y of cerium hydroxide until a test on Congo paper does not show any change of color. ts solution gives on litmus paper an acid reaction, on Congo paper a neutral reaction .andprecipitates glue with a brown color. Thed'ry substance chars when heated while strongly'putfing up without previously melting; it is readily soluble in water but insolublein ether and benzene. EwampZe,8.-.-.7 5 kilos of naphthalene and 75. kilos ofphenol are sulfonated with 150 kilo'sof sulfuric acid of 98 per cent stren h and the product is condensed with 75 kilos 5.. at 70-80 C.

thereto of kilos. of tannin it'is coupled with 50 kilos of-a formaldehyde solution of 30 per cent strength.

I-Therc are then introduced ash solution of 36 85 kilos of pot B. and cerium hydroxide added to the whole until atest does not change the colpr of Congo paper. The solution shows on litmus paper an acid reaction, on Congo paper a neutral reaction and it preci itates glue with a brownish col: oration. T e dry substance when heated on ether and benzene.

coal tarphenols' other known like are used a spatula chars without previously melting; it is readily soluble in water, insoluble in Example 9.7 5 kilos of naphthalene and 75 kilos'ofphenol are sulfonated at 120 C. for 8 hours with 150 kilos of sulfuric acid of 98 per cent strength and the product is condensed with kllOS of a formaldehyde solution of 30 per cent strength until a test with a glue solution does not show .anv further increase of the precipitation' The mass thus obtained before get-ting stiff "is diluted with 100 litres of water, neutralized with calcium hydroxide and filtered awhile hot. The resulting product is treated with sodium carbonate and the calcium carbonate is filtered off. The solution of the metal salt of the tanning substance is then run while stirring into a solution of chro mium chloridecontaining about 2 molecular proportions of chromium chloride calculated upon one molecule of the tanning substance, whereupon sodium carbonate is added for forming the basic salt until all of the hydrochloric acid is linked to sodium.

The solution shows on Congo paper a neut'ral reaction and when mixed with animal glue it gives a coplous precipitate. The d substance when heated chars without previously melti it is, soluble in water, but insoluble in ct er and benzene.

Instead of chromium chloride, other heavy metal compounds can be combined with artificial tanning substances so as to obtain the corresponding salts, and the reaction may of course also be effected by any process for the formation of basic salts. 8 Finally there may also be used for tanning animal hides alkaline earth metal salts of the above described tanning substances consisting of coupled organic components. Such salts ssess likewise the property of tanning animal hidesin solutions neutral to Congo paper, a factflhitherto unknown and u on which the forementioned advantages e end. a

c As is nown, calcium compounds and the with reluctance in tanneries because inmost cases they cause the leather to become brittle, hard and cracky, however, the calcium coupled with the aforedescribed artificial tanning substances does not exercise such detrimental action. 7

In German Patents Nos. 265,855, 266,139, 280,233 and 281,484 and in Austrian Patent .No. 69,194 are described artificial tanning substances consisting of coupled components to be used alone or mixed with other tanning or non-tanning materials but in these patents no reference whatever is made-to a chemical conversion of the respective compounds into alkaline earth metal salts capable of tanning in solutions neutral to Congo paper, but they only deal with mere mechanical mixtures of different bodies. The new products precipitate animal glue, are soluble in water and possess the properties of the ordinary tanning substances; they can be employed alone, or mixed with other tanning agents or other ingredients and they are also adapted for the combined tanning processes.

Example J0.The prepared unhaired skin is treated with a tanning liquor of about 2-3 per cent strength, the tanning substance of which hasbeen prepared as follows: 75 kilos of naphthalene and 7 5 kilos of phenol are sulfonated at 120 C. for 8 hours with 150 kilos of sulfuric acid of 98 per cent strength and the product is condensed at 80 C. with a formaldehyde solution of 30 per cent strength until a test with a glue solution does not show any further increase of the precipitate. The mass thus obtained before getting stiif is diluted with 100 litres of water, neutralized with calcium hydroxide and filtered while hot. The solution thus obtained can be used for tanning or it may be evaporated to dryness. The tanning operation is carried out, according to. the kind of skin, inthe tan pit, in the reel or in the fulling' trough, the strength of the-liquor and the duration of the tanning being adjusted accordingly.

Example 11 .The tanning is effected as indicated in example 1, with a tanning substance'prepared as hereafter described 100 kilos of coal tar phenols of melting point 185200 C. are mixed with 27 5 kilos of crystallized sodium sulfite, 275 litres of water and 150 kilos of a formaldehyde solution of 30 per cent strength and the whole is heated in an autoclave for about 8 hours at.140150 C. The product of the condensation is acidified by adding sulfuric acid and the sulfurous acid is boiled out. The resulting product is neutralized by means of calcium hydroxide until a test on Congo paper shows no change of color, whereupon it is filtered.

Example 12.The tanning is effected by means of a tanning substance prepared as follows kilos of naphthalene and 75 kilos of phenol are sulfonated with 150 kilos of sulfuric acid of 98 per cent strength and the product is condensed with 75 kilos of a formaldehyde solution of 30 per cent strength. The reaction mixture before getting stiff is diluted with 100 litres of water and after adding 50 kilos of tannin coupled at 70-80 C. with 50 kilos of a formaldehyde solution of 30 per centstrength. There is then added calcium hydroxide until there is a neutral reaction and the whole is filtered while hot.

Example 13.The tanning liquor is made up with a tannin substance prepared as follows: 23 kilos 0%2-6-naphtolsulfuric acid are mixed with a solution of 18 kilos of glucose in 10 litres of water and this mixture is caused to react at water bath temperature with 10 kilos of a formaldehyde solution of 30 percent strength. The product is dissolved in hot water, filtered and then is added calcium hydroxide until a test does not change the color of Congo paper.

The durationof all the above described tanning processes is about 24-60 hours according to the thickness of the leather to be obtained. The finished leather shows a lighter color as compared with that tanned with the natural tann'ing agents and its out is of an entirely uniform appearance.

Having now described my invention, what I claim is:

1. As new products, soluble tanning substances having the general formula:

Me Me l l in which X stands foran aromatic or'aliphatic radical, Y stands for an aromatic or aliphatic radical, Z stands for an aliphatic in which X stands for an aromatic radical, Y stands for an aromatic radical, Z stands for an aliphatic atomic group, and Me stands for an alkaline earth metal or a heavy metal.

4. As new products, soluble tanning substances having the general formula:

lYle I hide X Y in which X stands for an aliphatic or aromatic radical, Y stands for an aromatic radical, Z stands for an aliphatic atomic group, and Me stands for a heavy metal.

5. As new products, soluble tanning substances having the general formula:

in which X stands for an aliphatic or aromatic radical, Y stands for an aliphatic or lll) aromatic radical, Z stands for an ali hatic atomic group, and Me stands for a metal.

6. The process of preparing water soluble tanning substances capable of tanning animal hides in Congo neutral solution and having the general formula:

eavy

Me Me acid com ound in the resence of formaldehyde an subjecting t e condensation product in solution to the action of a nonacid compound of a metal the salts of which have tanning properties until a Congo neutral solution is formed.

7 The process of preparing new tanning agents which comprises condensing organic compounds containing a salt forming group in the presence of formaldehyde, coupling the condensation product with tannin, and treating the coupled product in solution with a compound of a heavy metal until the solution is neutral to Congo paper..

In testimony whereof I hereunto aflix my signature.

OSCAR LOW-BEER. 

